Conventionally, a multi-channel source separation technology of separating an acoustic signal of an arbitrary source from acoustic signals recorded from multi-channel sources has been employed in a signal processing system such as a conference system. In the multi-channel source separation technology, generally, an algorithm of comparing acoustic signals separated for the respective sources, increasing the degree of separation (independency and the like), based on the comparative result, and estimating the acoustic signal to be separated is used. At this time, a peak of directional characteristics is detected by preliminarily setting a threshold value depending on acoustic environment, and the acoustic signals of the sources separated based on the peak detection result are connected to the corresponding sources.
In actual employment, however, the acoustic signals of only one source do not continue being appropriately collected in one channel. This is because, for example, when two arbitrary signals are selected from the separated acoustic signals in a certain processing frame, the value of the objective function based on the degree of separation which compares the output signals is not varied even if channel numbers determined to respective output ends (often called channels) are replaced with each other. Actually, as a result of continuing use of the source separation system, changing a channel which continues outputting acoustic signals of a certain source to output acoustic signals of the other source occurs as a phenomenon. This phenomenon results from not failure in source separation, but remaining instability concerning the channel numbers output as mentioned above.
As mentioned above, the signal processing system based on the conventional multi-channel signal source separation technology has a problem that the generated signal of the only one signal source does not appropriately continue being collected to one channel, and the system is switched such that the generated signal of another signal source is output to the channel which continues outputting the generated signal of a certain signal source.
The embodiments have been accomplished in consideration of the above problem, and aims to provide a signal processing system, a signal processing method and a signal processing program which can continue outputting the generated signal derived from the same signal source to the same channel at any time, in multi-channel signal source separation.